Data Types in Node.js

Understand JavaScript data types: primitives, reference types, type checking, comparisons, and validations.

What Are Data Types?

Data types define what kind of value a variable can hold. JavaScript is dynamically typed, meaning types are decided at runtime.

1. Dynamic Typing

Variables can change their data type.

Primitive Data Types

Primitive data types store immutable values and are copied by value.

1. String

Textual data.

2. Number

Integer and floating-point numbers.

3. Boolean

true or false.

4. Undefined

Declared but not assigned.

5. Null

Intentional absence of value.

6. BigInt

Very large integers.

7. Symbol

Unique identifiers.

Reference Data Types

Reference types are copied by reference, not by value.

1. Object

Key-value pairs.

2. Array

Ordered list of values.

3. Function

Callable object.

Printing the Data Type

JavaScript provides the typeof operator to inspect data types.

1. Using typeof

Check the type of a value.

Comparing Data Types

You can compare data types using typeof in if-else or switch.

1. Type Check Using if-else

Compare types using typeof.

2. Type Check Using switch

Switch based on typeof.

Checking Arrays, Objects, and Functions

typeof alone is not enough for arrays and objects.

1. Checking if a Variable is an Array

Use Array.isArray().

2. Checking if a Variable is a Specific Object

Use classes and instanceof to check for a specific object type.

3. Checking if a Variable is a Function

Use typeof.